1. Field of the Invention
The present invention relates generally to medical devices and methods. More particularly, the present invention relates to systems and methods for optically scanning an interior surface of a body lumen to generate digital dimensional information relating to a lumen surface.
Minimally invasive implantation of vascular and other luminal prostheses has become widespread in the last ten years. The intravascular delivery and implantation of stent grafts for treating abdominal and other aneurysms is now common place for patients at risk for receiving open surgical implantation procedures. The percutaneous delivery and implantation of prosthetic aortic valves has recently become available and is quickly becoming a preferred treatment option for patients at risk for receiving open heart surgery. Both of these procedures, and other percutaneous therapeutic procedures, would benefit from characterization of the site of implantation prior to choosing the implant and performing the implantation procedure. Presently, external imaging, such as CT and MRI, is the most common technique for obtaining anatomical information regarding the implantation site. CT and MRI, however, provide limited dimensional information. The images which are obtained must be interpreted in order to derive dimensional information which is often inaccurate.
Intravascular ultrasound imaging (IVUS) can also be used to characterize aneurismal and valve replacement sites prior to implantation procedures. The IVUS probes are intravascularly placed within the blood vessel or heart. While the ultrasonic images may be improvements over those obtained by external scans, the images still lack the dimensional detail which would be desirable for selecting a prosthesis for subsequent implantation. These images also suffer from artifacts which make it difficult to interpret the anatomical boundaries of the structures, further leading to inaccuracy in determining dimensions.
A further shortcoming of both the external and internal imaging modalities is an inability to measure the luminal area and anatomical dimensions when the body lumen is under deformational stress equivalent to that provided by the prosthetic implant. For example, when planning the implantation of a prosthetic heart value, it would be useful to determine the dimensions of the valve annulus and surrounding tissues while the annulus was placed under a radially expansive force equivalent to that provided by the prosthetic implant. The conventionally utilized imaging methodologies do not allow measurement of the annulus diameter which would be assumed after a prosthetic device is deployed.
For these reasons, it would be desirable to provide improved methods, devices, and systems for obtaining dimensional information regarding an implantation site in a body lumen prior to actual implantation of a prosthesis. It would be particularly desirable if the dimensional information could be measured directly, not indirectly through image interpretation, and if the measurements could be made while the luminal site is under a stress or other deformational force which is analogous or equivalent to that which would be provided by the implant after implantation. It would be further desirable if the methods, devices and systems used for obtaining the measurement information could also obtain other information, such as color or other characteristics of the tissue being scanned during measurement. At least some of these objectives will be met by the inventions described below.
2. Description of the Background Art
Balloons and other devices for sizing valve annuluses and other lumens are described in U.S. Pat. Nos. 6,110,200; 6,755,861; and 8,246,628 and in U.S. Patent Publ. Nos. US2012/289982; US2012/065729; US2011/276127; US2011/237940; US2011/098602; US2010/198346; US2010/168839; US2007/244552; and US2005/075724.